Traction control upon start-up of automobile with continuously variable transmission

Abstract

A traction control of an automobile with a continuously variable transmission is provided. According to this control, in order to improve start-up ability of the vehicle on a road surface with a low friction coefficient, a wheel acceleration is derived and when the wheel acceleration is greater than a predetermined value, the tendency of the transmission to upshift is increased.

What is claimed is: 
     
       1. An automotive vehicle, comprising: an engine;   a continuously variable transmission having an input member drivingly connected to said engine and having an output member;   a driving wheel drivingly connected to said output member;   means for detecting a revolution speed of said input member and for generating an input revolution speed indicative signal indicative of said revolution speed of said input member detected; and   means for detecting a revolution speed of said output member and for generating a driving wheel revolution speed indicative signal indicative of said revolution speed of said output member detected;   wherein a driving wheel acceleration of said driving wheel is determined on the basis of said driving wheel revolution speed indicative signal, and a target input revolution speed at which said continuously variable transmission upshifts is modified when said driving wheel acceleration becomes equal to or greater than a predetermined acceleration value.   
     
     
       2. A method of a traction control of an automotive vehicle having an engine, a continuously variable transmission and a driving wheel, the continuously variable transmission including an input member drivingly connected to the engine and an output member drivingly connected to the driving wheel, the method comprising the steps of: detecting a revolution speed of the input member and generating an input revolution speed indicative signal indicative of said revolution speed of said input member detected;   detecting a revolution speed of the output member and generating a driving wheel revolution speed indicative signal indicative of said revolution speed of the output member detected;   determining a driving wheel acceleration of the driving wheel base on said driving wheel revolution speed indicative signal; and   modifying a target input revolution speed at which said continuously variable transmission upshifts when said driving wheel acceleration becomes equal to or greater than a predetermined acceleration value.   
     
     
       3. A method as claimed in claim 2, wherein said predetermined acceleration value is variable with a predetermined engine load indicative operating variable. 
     
     
       4. A method as claimed in claim 2, wherein the continuously variable transmission is shiftable in reduction ratio in such a manner as to decrease a deviation of an actual value of a predetermined reduction ratio related variable from a target value of said predetermined reduction ratio related variable. 
     
     
       5. A method as claimed in claim 4, wherein, when said driving wheel acceleration becomes equal to or greater than a predetermined acceleration value, said target value is leveled off at a predetermined value. 
     
     
       6. A method as claimed in claim 4, wherein, when said driving wheel acceleration becomes equal to or greater than a predetermined acceleration value, said target value is variable as a function of predetermined engine load indicative and vehicle speed indicative variables. 
     
     
       7. A method of a traction control of an automotive vehicle having an engine, a continuously variable transmission, and a driving wheel, the continuously variable transmission including an input member drivingly connected to the engine and an output member drivingly connected to the driving wheel, the method comprising the steps of: detecting a throttle valve opening degree of the engine and generating a throttle valve opening degree indicative signal indicative of said throttle valve opening degree detected;   detecting revolution speed of the input member and generating an input revolution speed indicative signal indicative of said revolution speed of said input member detected;   detecting a revolution speed of the output member and generating a driving wheel revolution speed indicative signal indicative of said revolution speed of the output member detected;   determining a driving wheel acceleration of the driving wheel based on said driving wheel revolution speed indicative signal and generating a driving wheel acceleration indicative signal indicative of said driving wheel acceleration determined;   determining a target value of said revolution speed of the input member as a predetermined function of said throttle valve opening degree indicative signal and said driving wheel revolution speed indicative signal and generating a target input revolution speed indicative signal indicative of said target value determined;   modifying said target input revolution speed indicative signal upon said target input revolution speed indicative signal being greater than or equal to a predetermined input revolution speed value when said driving wheel acceleration indicative signal is greater than or equal to a predetermined acceleration value and causing the continuously variable transmission to shift in reduction ratio so as to decrease a deviation of said input revolution speed indicative signal from said predetermined input revolution speed;   causing the continuously variable transmission to shift in reduction ratio so as to decrease a deviation of said input revolution speed indicative signal from said target input revolution speed indicative signal upon said target input revolution speed indicative signal being less than said predetermined input revolution speed value when said driving wheel acceleration indicative signal is greater than or equal to said predetermined acceleration value; and   causing the continuously variable transmission to shift in reduction ratio so as to decrease a deviation of said input revolution speed indicative signal from said target input revolution speed indicative signal when said driving wheel acceleration indicative signal is less than said predetermined acceleration value.   
     
     
       8. A method of a traction control of an automotive vehicle having an engine, a continuously variable transmission, and a driving wheel, the continuously variable transmission including an input member drivingly connected to the engine and an output member drivingly connected to the driving wheel, the method comprising the steps of: detecting a throttle valve opening degree of the engine and generating a throttle valve opening degree indicative signal indicative of said throttle valve opening degree detected;   detecting a revolution speed of the input member and generating an input revolution speed indicative signal indicative of said revolution speed of said input member detected;   detecting a revolution speed of the output member and generating a driving wheel revolution speed indicative signal indicative of said revolution speed of the output member detected;   determining a target value of said revolution speed of the input member as a predetermined function of said throttle valve opening degree indicative signal and said driving wheel revolution speed indicative signal and generating a target input revolution speed indicative signal indicative of said target value determined;   determining a driving wheel acceleration of the driving wheel based on said driving wheel revolution speed indicative signal and generating a driving wheel acceleration indicative signal indicative of said driving wheel acceleration determined;   modifying said target input revolution speed indicative signal when said driving wheel acceleration indicative signal is greater than or equal to a predetermined acceleration value and causing the continuously variable transmission to shift in reduction ratio so as to decrease a deviation of said input revolution speed indicative signal from said modified target input revolution speed indicative signals; and   causing the continuously variable transmission to shift in reduction ratio so as to decrease a deviation of said input revolution speed indicative signal from said target input revolution speed indicative signal when said driving wheel acceleration indicative signal is less than said predetermined acceleration value.